There is known a television camera system for broadcasting use or business use, provided with an autofocus function of automatically focusing on an object within a specific imaging area. This type camera system generally uses contrast-method AF which is performed by detecting the height of contrast of a captured image and controlling the focus of a capturing optical system to maximize (locally maximize) the contrast.
As to focusing by AF, focusing is generally performed not on the entire screen of the captured image but on an object within an area (autofocus area) which is a part of the captured image. That is, in the contrast method, focus adjustment is performed to maximize the contrast of the captured image (object image) within the autofocus area.
An autofocus system with an automatic tracking function as shown in Patent Literature 1 is known as a system to achieve the autofocus function. The autofocus system in Patent Literature 1 uses an AF mode in which either of a fixation mode to turn off the automatic tracking function and a tracking mode to turn on the automatic tracking function is selected by an operation of a user.